Evaluation on the Thermoelectric Cooling Ability of PbTe

High thermoelectric cooling efficiency requires a high average ZT value, especially in a low temperature range. PbTe-based compounds are typical intermediate-temperature thermoelectric materials due to their relatively low ZT values near room temperature. Here, we attempt to enhance the average ZT value of PbTe, especially at 300–600 K, through decreasing its band gap so as to evaluate the thermoelectric cooling performance. The results show that Sn alloying in PbTe can narrow its band gap from ∼0.28 to ∼0.18 eV, which shifts its peak power factor from 673 to 523 K. Combining the enhanced power factor with the reduced lattice thermal conductivity after Sn alloying, a maximum average ZT value of ∼0.74 is obtained in n-type Pb0.785Sn0.2Sb0.015Te at 300–723 K. Finally, the thermoelectric cooling performance of a Pb0.785Sn0.2Sb0.015Te-based single leg is measured, and a cooling ΔTmax of ∼15 K is realized. These results demonstrate that, after tuning the band gap, PbTe can also exhibit promising cooling performance even though it is a typical intermediate-temperature thermoelectric material.